[P2-132] Phenytoin－Withdrawal Seizures and Exacerbating Combinations of AEDs
Phenytoin(PHT) withdrawal when weaning patients from multiple to single therapies frequently precipitates status epilepticus. There are, however, few descriptions of PHT withdrawal seizures or the underlying mechanisms.
This patient, a male, developed spasms at age five months, and was diagnosed with West syndrome, Lennox-Gastaut syndrome and intractable epilepsy. He was admitted to our hospital at age 23 years and had been prescribed the same regimen of AEDs, including PHT, VPA, CLB and ZNA, for most of his life. He still had tonic spasms and generalized tonic/tonic-clonic seizures on an almost daily basis, with occasional status epilepticus. He also presented with signs of chronic PHT intoxications. His AEDs regimen was gradually, over a period of one year, switched to VPA monotherapy. However, seizure severity had worsened to cluster and acute febrile status epilepticus, necessitating the administration of massive doses of midazolam, frequent diazepam and high-dose VPA. He is now 41 years old and is being treated with VPA, 80-90μg/ml. His seizure frequency has decreased to once every 4-7days. Major Laboratory Findings: RBBB, ventricular and supraventricular extra-systoles, and AV block
were demonstrated by ECG. Fe and Zn deficiency anemia and CD4/helper T-cell reduction, and elevated serum insulin and erythropoietin levels were revealed.
Discussion and Conclusion: Zn deficiency caused CD4 cell/helper T-cell reduction and dysfunction, rendering this patient susceptible to infections, with high fever and pneumonia, which triggered acute febrile status epilepticus. The RBBB had been identified at age 8 years, about 5 years after starting PHT administration. Prolonged serum VPA elevation might have caused insensitivity to multiple receptors. Long-term usage of CLB might also cause benzodiazepine receptor insensitivity. PHT in combination with other AEDs, including VPA and benzodiazepines, might portend intractable withdrawal seizures.
This patient, a male, developed spasms at age five months, and was diagnosed with West syndrome, Lennox-Gastaut syndrome and intractable epilepsy. He was admitted to our hospital at age 23 years and had been prescribed the same regimen of AEDs, including PHT, VPA, CLB and ZNA, for most of his life. He still had tonic spasms and generalized tonic/tonic-clonic seizures on an almost daily basis, with occasional status epilepticus. He also presented with signs of chronic PHT intoxications. His AEDs regimen was gradually, over a period of one year, switched to VPA monotherapy. However, seizure severity had worsened to cluster and acute febrile status epilepticus, necessitating the administration of massive doses of midazolam, frequent diazepam and high-dose VPA. He is now 41 years old and is being treated with VPA, 80-90μg/ml. His seizure frequency has decreased to once every 4-7days. Major Laboratory Findings: RBBB, ventricular and supraventricular extra-systoles, and AV block
were demonstrated by ECG. Fe and Zn deficiency anemia and CD4/helper T-cell reduction, and elevated serum insulin and erythropoietin levels were revealed.
Discussion and Conclusion: Zn deficiency caused CD4 cell/helper T-cell reduction and dysfunction, rendering this patient susceptible to infections, with high fever and pneumonia, which triggered acute febrile status epilepticus. The RBBB had been identified at age 8 years, about 5 years after starting PHT administration. Prolonged serum VPA elevation might have caused insensitivity to multiple receptors. Long-term usage of CLB might also cause benzodiazepine receptor insensitivity. PHT in combination with other AEDs, including VPA and benzodiazepines, might portend intractable withdrawal seizures.